RPM-Based Fan Controller with HW Thermal Shutdown
Datasheet
(THERMTRIP#) and power supply (POWER_OK) and configuration information from the fixed states
of the SHDN_SEL pins as described in Section 5.7.2.
In addition, each of the temperature limits can be configured to act as inputs to the Critical / Thermal
Shutdown independent of the hardware shutdown operation.
The analog portion of the Critical/Thermal Shutdown function monitors a specific remote temperature
channel (configured with the SHDN_SEL pin). This measured temperature is then compared with the
TRIP_SET point. This TRIP_SET point is created by the system designer with a simple resistor divider
and is discussed in detail in Section 5.7.1.
Critical Shutdown Logic
H/W Set Sensor
SMBus Traffic
SYS1 - SYS3
Configuration
Register
Temperature
Conversion
and Limit
SW_SHDN
S/W Set Sensor
S/W Set Sensor
Registers
‘0’ or ‘open’
SHDN_SEL
PIN Decode
‘1’
H/W Critical
Sensor
Temperature
Conversion
3.3V
HW_SHDN
TRIP_SET
Voltage
Conversion
SYS_SHDN#
Thermal_SHDN
Thermal
Shutdown
THERMTRIP#
POWER_OK
From CPU /
Chipset
ThermTrip_
SHDN
From the
Power Supply
ThermTrip# Power_OK ThermTrip_SHDN
0
0
1
1
0
1
0
1
0
1
0
0
Figure 5.4 EMC2102 Critical/Thermal Shutdown Block Diagram
SMSC EMC2102
Revision 1.95 (10-19-06)
DATA2S7HEET
SMSC [ SMSC CORPORATION ]
